Method and apparatus of using redundant bits in semi-statically configured HARQ-ACK codebook

ABSTRACT

The present application is related to a method and apparatus of using redundant bits in semi-statically configured HARQ-ACK feedback. A method of receiving information according to one embodiment comprises receiving a first number of code block groups from a base unit, wherein each code block within a code block group is independently decodable; determining a (HARQ-ACK) codebook size corresponding to the first number of code block groups; and transmitting a HARQ-ACK codebook to the base unit, wherein the HARQ-ACK codebook comprises the first number of HARQ-ACK bits with each bit corresponding to one code block group and a second number of padded bits. The first number plus the second number is equal to the determined HARQ-ACK codebook size. The present application enhances the downlink (DL) transmission performance and the uplink (UL) HARQ-ACK transmission reliability.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 16/638,438filed on Feb. 11, 2020, which is hereby incorporated by reference in itsentirety.

TECHNICAL FIELD

The present application generally relates to hybrid automatic repeatrequest-acknowledge (HARQ-ACK) feedback, and more specifically tosemi-statically configured HARQ-ACK codebook.

BACKGROUND OF THE INVENTION

In wireless communication technology, HARQ-ACK feedback technology iscommonly used during data transmission, so as to feedback whether datawas correctly received in the downlink (DL) or uplink (UL) transmission.HARQ-ACK represents collectively the Positive Acknowledgement (ACK) andthe Negative Acknowledgement (NACK). ACK means data was correctlyreceived while NACK means data was erroneously received. For HARQ-ACKfeedback information (which may be called as a HARQ-ACK codebook, forexample), the HARQ-ACK codebook size is usually preconfigured and/ordetermined during transmission. However, in some cases, not all of theHARQ-ACK bits in the HARQ-ACK book are actually useful for HARQ-ACKfeedback for a data transmission, other useless bits may be calledredundant bits. On the basis of the shortage of wireless networkresources, redundant bits in HARQ-ACK feedback information thus renderlow efficiency of data transmission in the wireless communication.

A manner of fully using redundant bits in the HARQ-ACK feedbackinformation is desirable.

BRIEF SUMMARY OF THE INVENTION

One objective of the present application is to provide a manner of fullyusing redundant bits in the HARQ-ACK feedback information.

One embodiment of the present application provides a method. The methodincludes receiving a first number of code block groups from a base unit,wherein each code block within a code block group is independentlydecodable; a hybrid automatic repeat request acknowledgement (HARQ-ACK)codebook size corresponding to the first number of code block groups isdetermined; a HARQ-ACK codebook is transmitted to the base unit, whereinthe HARQ-ACK codebook includes the first number of HARQ-ACK bits witheach bit corresponding to one code block group and a second number ofpadded bits, wherein the first number plus the second number is equal tothe determined HARQ-ACK codebook size.

Another embodiment of the present application also provides anapparatus. The apparatus includes a receiver that receives a firstnumber of code block groups from a base unit, wherein each code blockwithin a code block group is independently decodable; a processor thatdetermines a hybrid automatic repeat request acknowledgement (HARQ-ACK)codebook size corresponds to the first number of code block groups; anda transmitter that transmits a HARQ-ACK codebook to the base unit,wherein the HARQ-ACK codebook includes the first number of HARQ-ACK bitswith each bit corresponding to one code block group and a second numberof padded bits, wherein the first number plus the second number is equalto the determined HARQ-ACK codebook size.

Yet another embodiment of the present application also provides amethod. The method includes transmitting a first number of code blockgroups to a remote unit, wherein each code block within a code blockgroup is independently decodable; a hybrid automatic repeat requestacknowledgement (HARQ-ACK) codebook size corresponding to the firstnumber of code block groups is determined; and a HARQ-ACK codebook isreceived from the remote unit, wherein the HARQ-ACK codebook includesthe first number of HARQ-ACK bits with each bit corresponding to onecode block group and a second number of padded bits, wherein the firstnumber plus the second number is equal to the determined HARQ-ACKcodebook size.

A further embodiment of the present application also provides anapparatus. The apparatus includes a transmitter that transmits a firstnumber of code block groups to a remote unit, wherein each code blockwithin a code block group is independently decodable; a processor thatdetermines a hybrid automatic repeat request acknowledgement (HARQ-ACK)codebook size corresponds to the first number of code block groups; areceiver that receives a HARQ-ACK codebook from the remote unit, whereinthe HARQ-ACK codebook includes the first number of HARQ-ACK bits witheach bit corresponding to one code block group and a second number ofpadded bits, wherein the first number plus the second number is equal tothe determined HARQ-ACK codebook size.

Embodiments according to the present application can enhance theperformance of downlink (DL) transmission and the reliability of uplink(UL) HARQ-ACK transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of thepresent application can be obtained, a description of the presentapplication is rendered by reference to specific embodiments thereofwhich are illustrated in the appended drawings. These drawings depictonly example embodiments of the present application and are nottherefore to be considered as limiting of its scope.

FIG. 1 illustrates an example block diagram of a wireless communicationsystem according to an embodiment of the present application.

FIG. 2 illustrates an example flowchart demonstrating the operations ofa remote unit according to an embodiment of the present application.

FIG. 3 illustrates an example of generating and padding redundant bitsin HARQ-ACK codebook according to an embodiment of the presentapplication.

FIG. 4 illustrates an example of generating and padding redundant bitsin HARQ-ACK codebook according to an embodiment of the presentapplication.

FIG. 5 illustrates an example of generating and padding redundant bitsin HARQ-ACK codebook according to an embodiment of the presentapplication.

FIG. 6 illustrates an example flowchart demonstrating the operations ofa base unit according to an embodiment of the present application.

FIG. 7 is an example block diagram of a remote unit according to anembodiment of the present application.

FIG. 8 is an example block diagram of a base unit according to anembodiment of the present application.

DETAILED DESCRIPTION OF THE INVENTION

The detailed description of the appended drawings is intended as adescription of the currently preferred embodiments of the presentinvention, and is not intended to represent the only form in which thepresent invention may be practiced. It should be understood that thesame or equivalent functions may be accomplished by differentembodiments that are intended to be encompassed within the spirit andscope of the present invention.

Embodiments provide the method and apparatus for using redundant bits insemi-statically configured HARQ-ACK feedback information. To facilitateunderstanding, embodiments are provided under specific networkarchitecture and new service scenarios, such as 3GPP 5G, 3GPP LTERelease 8 and onwards. Persons skilled in the art know well that, withdevelopments of network architecture and new service scenarios, theembodiments in the subject disclosure are also applicable to similartechnical problems.

FIG. 1 depicts a wireless communication system 100 according to anembodiment of the present application.

As shown in FIG. 1, the wireless communication system 100 includesremote units 101 and base units 102. Even though a specific number ofremote units 101 and base units 102 are depicted in FIG. 1, one of skillin the art will recognize that any number of remote units 101 and baseunits 102 may be included in the wireless communication system 100.

The remote units 101 may include computing devices, such as desktopcomputers, laptop computers, personal digital assistants (PDAs), tabletcomputers, smart televisions (e.g., televisions connected to theInternet), set-top boxes, game consoles, security systems (includingsecurity cameras), vehicle on-board computers, network devices (e.g.,routers, switches, modems), or the like. According to an embodiment ofthe present application, the remote units 101 may include a portablewireless communication device, a smart phone, a cellular telephone, aflip phone, a device having a subscriber identity module, a personalcomputer, a selective call receiver, or any other device that is capableof sending and receiving communication signals on a wireless network. Insome embodiments, the remote units 101 include wearable devices, such assmart watches, fitness bands, optical head-mounted displays, or thelike. Moreover, the remote units 101 may be referred to as subscriberunits, mobiles, mobile stations, users, terminals, mobile terminals,wireless terminals, fixed terminals, subscriber stations, UE, userterminals, a device, or by other terminology used in the art. The remoteunits 101 may communicate directly with a base unit 102 via uplink (UL)communication signals.

The base units 102 may be distributed over a geographic region. Incertain embodiments, a base unit 102 may also be referred to as anaccess point, an access terminal, a base, a base station, a macro cell,a Node-B, an enhanced Node B (eNB), a gNB, a Home Node-B, a relay node,a device, or by any other terminology used in the art. The base units102 are generally part of a radio access network that may include one ormore controllers communicably coupled to one or more corresponding baseunits 102.

The base units 102 are generally communicably coupled to one or morepacket core networks (PCN), which may be coupled to other networks, likethe packet data network (PDN) (e.g., the Internet) and public switchedtelephone networks, among other networks. These and other elements ofradio access and core networks are not illustrated but are well knowngenerally by those having ordinary skill in the art. For example, one ormore base units 102 may be communicably coupled to a mobility managemententity (MME), a serving gateway (SGW), and/or a packet data networkgateway (PGW).

The base units 102 may serve a number of remote units 101 within aserving area, for example, a cell or a cell sector via a wirelesscommunication link. The base units 102 may communicate directly with oneor more of the remote units 101 via communication signals. For example,a base unit 102 may serve remote units 101 within a macro cell.

The base units 102 transmits downlink (DL) communication signals toserve the remote units 101 in the time, frequency, and/or spatialdomain. Furthermore, the DL communication signals may be carried overwireless communication links. The wireless communication links may beany suitable carrier in licensed or unlicensed radio spectrum. Thewireless communication links facilitate communication between the remoteunits 101 and the base units 102.

The wireless communication system 100 is compliant with any type ofnetwork that is capable of sending and receiving wireless communicationsignals. For example, the wireless communication system 100 is compliantwith a wireless communication network, a cellular telephone network, aTime Division Multiple Access (TDMA)-based network, a Code DivisionMultiple Access (CDMA)-based network, an Orthogonal Frequency DivisionMultiple Access (OFDMA)-based network, a Long Term Evolution (LTE)network, a 3rd Generation Partnership Project (3GPP)-based network, 3GPP5G network, a satellite communications network, a high altitude platformnetwork, and/or other communications networks.

In one implementation, the wireless communication system 100 iscompliant with the long-term evolution (LTE) of the 3GPP protocol,wherein the base unit 102 transmits using an orthogonal frequencydivision multiplexing (OFDM) modulation scheme on the DL and the remoteunits 101 transmit on the UL using a single-carrier frequency divisionmultiple access (SC-FDMA) scheme or OFDM scheme. More generally,however, the wireless communication system 100 may implement some otheropen or proprietary communication protocol, for example, WiMAX, amongother protocols.

In other embodiments, the base unit 102 may communicate using othercommunication protocols, such as the IEEE 802.11 family of wirelesscommunication protocols. Further, in some embodiments the base unit 102may communicate over licensed spectrum, while in other embodiments thebase unit 102 may communicate over unlicensed spectrum. The presentdisclosure is not intended to be limited to the implementation of anyparticular wireless communication system architecture or protocol. Inanother embodiment, the base unit 102 may communicate with remote units101 using the 3GPP 5G protocols.

According to an embodiment of the present application, downlink (DL)transport blocks (TBs) are carried on the Physical Downlink SharedChannel (PDSCH). A maximum of two TBs can be transmitted in one PDSCH inone serving cell and in one sub-frame. One TB includes a plurality ofcode blocks, several code blocks in a TB are grouped into one code blockgroup (CBG), and each code block within a code block group isindependently decodable. That is, a TB includes a plurality of CBGs. Thenumber of code blocks of one CBG, i.e., CBG size, varies according tothe TB size. Based on the number of CBGs, a wireless communicationdevice, for example, a UE, can generate a single bit for each CBG thenconcatenate the generated bits in one HARQ-ACK codebook. That is, oneHARQ-ACK bit corresponds to one CBG, and the number of resultingHARQ-ACK bits for one TB may be equal to the number of code blockgroups. That will balance the number of the needed HARQ-ACK feedbackbits and the retransmission efficiency.

The number of code block groups of one TB can be configured via RadioResource Control (RRC) signaling.

When all the code blocks within one CBG are correctly decoded, theHARQ-ACK for the CBG is set to “ACK.” Otherwise, it is set to “NACK.”Upon the reception of the HARQ-ACK feedback, the CBG(s) with “NACK”shall be retransmitted by the transmitter. Meanwhile, the wirelessreceiving device, for example, a UE, will combine the receivedretransmitted CBG(s) with the previously incorrectly decoded CBG(s) forfurther decoding. Hence, the wireless transmitting device (for example,a BS) and the wireless receiving device could have the sameunderstanding on CBG construction, CBG indication, number of HARQ-ACKfeedback bits as well as the mapping relationship between one HARQ-ACKbit and one CBG. The wireless transmitting device and the wirelessreceiving device may synchronize the knowledge on the HARQ-ACK codebookin each transmission or retransmission to avoid any misunderstanding.

According an embodiment of the present application, a manner ofdetermining the HARQ-ACK codebook size for retransmitted CBG(s),HARQ-ACK codebook size is equal to the RRC configured number of CBGs forone TB. Then the HARQ-ACK codebook size is semi-statically configuredand not variable between retransmission and initial transmission.

FIG. 2 depicts a method 200 according to an embodiment of the presentapplication. In some embodiments, the method 200 is performed by anapparatus, such as the remote units 101. In certain embodiments, themethod 200 may be performed by a processor executing program code, forexample, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliaryprocessing unit, a FPGA, or the like.

In step 201, a number of CBGs is received from a base unit. In step 202,a HARQ-ACK codebook size is determined. For example, a HARQ-ACK codebooksize corresponding to the number of received CBGs is determined. In step203, a HARQ-ACK codebook having the determined HARQ-ACK codebook size istransmitted to the base unit. In one embodiment, a first portion of theHARQ-ACK codebook includes a number of HARQ-ACK bits with each bitcorresponding to one CBG, and a second portion of the HARQ-ACK codebookincludes a number of padded bits. The sum of the number of HARQ-ACK bitsin the first portion and the number of padded bits in the second portionis equal to the determined HARQ-ACK codebook size.

In one embodiment, the HARQ-ACK codebook size is determined based on apreconfigured value. The preconfigured value may be indicated by asignal received from a base unit, indicated by a control signalingreceived before the data transmission, or indicated by a controlsignaling received during the data transmission.

For example, the number of HARQ-ACK bits in the first portion, e.g., M,is equal to the number of CBGs actually received by a remote unit ininitial transmission or retransmitted CBGs in retransmission between abase unit and the remote unit. Assuming N is the RRC configured maximumnumber of CBGs of one TB, so (N−M) is the number of padded bits in thesecond portion of the HARQ-ACK codebook corresponding to the initialtransmission or retransmission.

For an additional example, the RRC configured number of CBGs for one TBis four, the HARQ-ACK codebook size is determined as four, and there arefour CBGs transmitted in initial transmission. That is, N=4. However,when two CBGs are not correctly received or not successfully decoded ininitial transmission, these two CBGs need to be retransmitted and thenumber of retransmitted CBGs is two. Accordingly, for semi-staticHARQ-ACK codebook size determination, two HARQ-ACK bits in a HARQ-ACKcodebook for the initial transmission are set to NACK, and the other twoHARQ-ACK bits in the HARQ-ACK codebook for the initial transmission areset to ACK. Under this situation, M=4 and (N−M)=0. There is no redundantbit in the HARQ-ACK codebook. Then, after retransmitting two CBGs whichare not correctly received or not successfully decoded in initialtransmission, the number of retransmitted CBGs may be two, one, or zero.In other words, when both the retransmitted two CBGs are not correctlyreceived or successfully decoded, the erroneous CBG(s) needs to beretransmitted again. For instance, when one CBG needs to beretransmitted again, one HARQ-ACK bit in a HARQ-ACK codebook for theretransmission is set to NACK, one HARQ-ACK bit in the HARQ-ACK codebookfor the retransmission is set to ACK. Under this situation, forsemi-static HARQ-ACK codebook size determination, M=2, (N−M)=2, theHARQ-ACK codebook includes two redundant bits, and these two redundantbits need to be padded to guarantee the number of HARQ-ACK codebooksize, i.e., N=4.

For another example, the RRC configured number of CBGs for one TB isfour, the HARQ-ACK codebook size is determined as four, i.e., N=4. In acertain embodiment, when the number of CBs in one TB is smaller than theRRC configured number of CBGs of one TB, e.g., when there are three CBsfor a given TB, then there are three CBGs with each CBG including one CBin initial transmission. For semi-static HARQ-ACK codebook sizedetermination, one redundant bit in the HARQ-ACK codebook for theinitial transmission needs to be padded in addition to the threeACK/NACK bits, so as to guarantee the number of HARQ-ACK bits in thecodebook to equal to the RRC configured number of CBGs of one TB, i.e.,N=4. For instance, when one CBG is not successfully decoded in initialtransmission, one HARQ-ACK bit in a HARQ-ACK codebook for the initialtransmission is set to NACK, two HARQ-ACK bits in the HARQ-ACK codebookfor the initial transmission are set to ACK, while the other oneredundant bit needs to be padded, i.e., M=3 and (N−M)=1. Then, afterretransmitting the CBG which was not successfully decoded in initialtransmission, the number of retransmitted CBG may be 1 or 0. In otherwords, when the retransmitted CBG was not correctly received orsuccessfully decoded during this retransmission again, the erroneous CBGneeds to be retransmitted for the second time. Accordingly, one HARQ-ACKbit in a HARQ-ACK codebook for the retransmission is set to NACK, i.e.,M=1, and (N−M)=3. Thus, the HARQ-ACK codebook includes three redundantbits and these three redundant bits need to be padded to guarantee thenumber of HARQ-ACK codebook size, N=4.

Embodiments can provide multiple examples of making full use of theredundant bits for semi-static CBG-based HARQ-ACK codebook size so as toenhance the DL transmission performance and UL HARQ-ACK transmissionreliability. Since the value of N and M are known to both thetransmitter (for example, a base unit) and the receiver (for example, aremote unit), the number of (N−M) bits are known to both sides. Twoexamples are shown in FIGS. 3 and 4.

According to an embodiment, after generating M HARQ-ACK feedback bitscorresponding to M actually (re)transmitted CBGs, a remote unitconcatenates the M HARQ-ACK feedback bits in ascending order of CBGindex. Alternatively, the M HARQ-ACK feedback bits may be in descendingorder or in other orders. The (N−M) redundant bits are generated byrepeating the values of M HARQ-ACK feedback bits till (N−M) redundantbits are fully padded. For instance, the (N−M) redundant bits carry(N−M) copies of the HARQ-ACK feedback bit when M=1. For anotherinstance, the (N−M) redundant bits can carry a copy/copies and/or aportion of the M HARQ-ACK feedback bits. E.g., N=8, M=3, (N−M)=5, thenthe five redundant bits are generated by repeating the three HARQ-ACKfeedback bits once and repeating two bits within the three HARQ-ACKfeedback bits the second time.

In one example, the padded bits are appended in the M HARQ-ACK feedbackbits as illustrated in FIG. 3. In another example, the padded bits arerandomly arranged in the (N−M) redundant bits between the M HARQ-ACKbits.

According to an embodiment, the M HARQ-ACK feedback bits are encoded via(3, 2) coding and the redundant bits are used for transmission ofencoded parity check bits. According to another embodiment, the MHARQ-ACK feedback bits are cyclic redundancy check (CRC) bits of the MHARQ-ACK feedback bits and the (N−M) redundant bits are used fortransmission of the CRC bits. The following embodiments of fully using(N−M) redundant bits are under the parity check mechanism, but notlimited to this check mechanism; for example, these embodiments arecertainly applicable for the CRC check mechanism.

Particularly, in one embodiment, when M=1, then (N−M) redundant bits aregenerated by repeating the HARQ-ACK feedback bit (N−M) times; when M>1,the M HARQ-ACK feedback bits include

$\left\lfloor \frac{M}{2} \right\rfloor$bit pairs and (M mod 2) remaining bit (s). The

$\left\lfloor \frac{M}{2} \right\rfloor$bit pairs in the M HARQ-ACK feedback bits may be encoded to

$\left\lfloor \frac{M}{2} \right\rfloor$parity check bits, and one bit pair is encoded to one parity check bit.

In one embodiment, when

${{N - M} \geq \left\lfloor \frac{M}{2} \right\rfloor},$the (N−M) redundant bits are generated by cyclically repeating theencoded

$\left\lfloor \frac{M}{2} \right\rfloor$parity check bits. Accordingly, the (N−M) redundant bits can carry acopy/copies and/or a portion of the encoded

$\left\lfloor \frac{M}{2} \right\rfloor$parity check bits. E.g., N=8, M=5, (N−M)=3, then the five HARQ-ACKfeedback bits include two bit pairs and one remaining bit, and the threeredundant bits are generated by repeating two encoded parity check bitsof the two bit pairs once and repeating the first encoded parity checkbit another time.

In another embodiment, when

${{N - M} < \left\lfloor \frac{M}{2} \right\rfloor},$the (N−M) redundant bits are a portion (e.g., the first (N−M) paritycheck bits) within the encoded parity check bits of

$\left\lfloor \frac{M}{2} \right\rfloor$bit pairs of the M HARQ-ACK feedback bits.

In one example, the encoded parity check bits of

$\left\lfloor \frac{M}{2} \right\rfloor$bit pairs of the M HARQ-ACK feedback bits are appended in the M HARQ-ACKbits in the HARQ-ACK codebook, as illustrated in FIG. 4.

In another example, the encoded parity check bits of

$\left\lfloor \frac{M}{2} \right\rfloor$bit pairs of the M HARQ-ACK feedback bits may be inserted between the

$\left\lfloor \frac{M}{2} \right\rfloor$bit pairs of the M HARQ-ACK feedback bits in the HARQ-ACK codebook. Fora certain example, each encoded parity check bit may be inserted at theend of each corresponding bit pair within the

$\left\lfloor \frac{M}{2} \right\rfloor$bit pairs of the M HARQ-ACK feedback bits, as illustrated in FIG. 5. Asshown in FIG. 5, P1 is a parity check bit of b00 and b01. In oneembodiment, b00 and b01 can be encoded via (3, 2) coding. In the exampleof

${{N - M} < \left\lfloor \frac{M}{2} \right\rfloor},$each of a portion (e.g., the first (N−M) parity check bits) within

$\left\lfloor \frac{M}{2} \right\rfloor$parity check bits is inserted at the end of the corresponding first(N−M) bit pairs. In the example of

${{N - M} \geq \left\lfloor \frac{M}{2} \right\rfloor},$optionally, the

$\left( {N - M - \left\lfloor \frac{M}{2} \right\rfloor} \right)$redundant bits are appended at the end with NACK indication. In anotheroption, the

$\left( {N - M - \left\lfloor \frac{M}{2} \right\rfloor} \right)$bits are appended at the end with cyclically repeated M HARQ-ACKfeedback bits.

In another example, M HARQ-ACK feedback bits (M ACK/NACK bits) may beprotected with CRC check. The (N−M) redundant bits are padded by thefirst (N−M) bits of the CRC parity check bits. For instance, the CRCwith bit length to 8 may be used to encode the M ACK/NACK bits, thefirst (N−M) parity check bits are padded following the M ACK/NACK bitswhen (N−M)<8. In an example of (N−M)>=8, the (N−M) redundant bits aregenerated by cyclically repeating the 8-bit CRC bits. In anotherembodiment, one-bit odd-even parity check bit can be transmitted in oneof the (N−M) redundant bits. For example, when there is even-number “1”in the M useful bits, the one-bit parity check bit is set “1”;otherwise, the one-bit parity check bit is set to “0” or vice versa.

According to an embodiment, a request signaling for adjustment of amodulation and coding scheme (MCS) can be transmitted in the (N−M)redundant bits in the HARQ-ACK codebook. This request signaling foradjustment of MCS can be generated by the remote unit based on thesignal to interference plus noise ratio (SINR) experienced in the PDSCH(or PUSCH) transmissions that the remote unit has received correspondingto the current TB. Even when a remote unit cannot decode the CBscorrectly, the remote unit can still estimate the received SINR usinghard decoding. Suppose the SINR estimated by the remote unit correspondsto MCS_(R) and the MCS received by the remote unit in the last PDSCH (orPUSCH) is MCS_(T). Although the base unit determines the MCS_(R) used inthe transmission based on some estimation or feedback (such as channelquality indicator (CQI) in the Channel State Information (CSI) feedback,or the ACK/NACK from the previous transmission), it is still possiblefor the received SINR to be lower than its expectation. For example, theused CQI is wide-band only, and the quality of the narrow band frequencyselective channel is below the reported channel quality of the wide bandchannel.

In one embodiment, when the remote unit provides the CSI report based onthe single-user-MIMO (SU-MIMO) assumption, and the transmitter uses amultiple-user-MIMO (MU-MIMO) pre-coder for MU transmission, or theremote unit simply suffers poor SINR from an extra-strong interferencefrom neighboring cell (the flash-light effect), the base unit could alsooverestimate the received SINR due to the difference in the transmissionpre-coder when a different transmitted precoding matrix indicator (TPMI)is used than the precoding matrix indicator (PMI) feedback. Because theMCS_(T) derived from the received transmissions, it accurately reflectsthe quality of the received transmission and is useful for the base unitto determine the MCS used in the next transmission. The remote unit cansignal the difference ΔMCS=MCS_(T)−MCS_(R) between the remote unit andthe base unit using the available number of bits, e.g., the (N−M)redundant bits in the HARQ-ACK codebook.

The following Table 1 shows examples of values of differenceΔMCS=MCS_(T)−MCS_(R).

TABLE 1 examples of the difference ΔMCS = MCS_(T) − MCS_(R) # of bits (N− M) ΔMCS = MCS_(T) − MCS_(R) 0 N/A 1 0: 0 1: −a1 2 00: 0 01: −a2 10−-b2 11: −c2 3 Option 1: use 3 bits for ΔMCS encoding. 000: 0 001: −a3010: −b3 011: −c3 100: −d3 101: −e3 110: −f3 111:−g3 Option 2: use only2 bits ΔMCS encoding as (N − M) = 2 case. 00: 0 01: −a2 10: −b2 11: −c2The remaining bit (s) in the (N − M) redundant bits may he reserved forother usage. >3 Similar to 3 bits case. The remaining bit (s) in the (N− M) redundant bits maybe reserved for other usage.

For example, the parameters {a1, a2, b2, . . . } are positive integersand these parameters can be defined in the spec, or configured by eNB orgNB through RRC signaling. An implementation is a1=a2=a3=1, b2=b3=2,c2=c3=3, d3=4, e3=5, f3=6, g3=7. Other values are possible. Because ofthe limited feedback states (2, 4 or 8), a remote unit may choose to useround or ceiling to match its AMCS to an encoded value for feedback. Onreceiving the AMCS, the base unit may adjust its MCS for the next(re)transmission to this UE.

Using the (N−M) redundant bits in the HARQ-ACK codebook for a remoteunit to request real-time MCS adjustment gives a new way for thetransmitter to get MCS information. In the traditional scheme, the baseunit gets MCS (CQI) information from the feedback based on not real, buttransmission with delays, with assumptions on the SU/MU-MIMO (usually itis SU-MIMO), on the PMI and on the interference. When MCS adjustment issent to the base unit, the MCS adjustment provides the base unit with arealistic and accurate representation of the transmission quality.Factors that affect the received SINR, like the channel in the usedphysical resource blocks (PRBs), the TPMI and the real time interferenceare naturally factored in. This MCS feedback used in the (N−M) redundantbits in the HARQ-ACK codebook is also sent over a short interval oftransmission and retransmission. It will improve the performance overmore traditional feedback and link adaptation scheme based on the CSIfeedback and the ACK/NACK feedback.

According to another embodiment, a channel quality indicator (CQI)feedback is carried by the (N−M) redundant bits in the HARQ-ACKcodebook. The amount of CQI feedback is dependent on the number of the(N−M) redundant bits. For example, 4 bits are needed to indicate theCQI; when N−M>=4, the redundant bits are enough to indicate one specificCQI index; otherwise, a reduced CQI table is carried by the (N−M)redundant bits in the HARQ-ACK codebook.

In all the above embodiments, the redundant bits can be fully used toenhance the DL transmission performance and UL HARQ-ACK transmissionreliability.

FIG. 6 depicts a method 600 according to an embodiment of the presentapplication. In some embodiments, the method 600 is performed by anapparatus, such as the base units 102. In certain embodiments, themethod 600 may be performed by a processor executing program code, forexample, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliaryprocessing unit, a FPGA, or the like.

In step 601, a number of CBGs is transmitted to a remote unit. In step602, a HARQ-ACK codebook size is determined. For example, a HARQ-ACKcodebook size corresponding to the number of transmitted CBGs isdetermined. In one embodiment, the HARQ-ACK codebook size is determinedbased on a preconfigured value. The preconfigured value may be indicatedby a signal received from a base unit, indicated by a control signalingreceived before the data transmission, or indicated by a controlsignaling received during the data transmission. In step 603, a HARQ-ACKcodebook having the determined HARQ-ACK codebook size is received fromthe remote unit. In one embodiment, a first portion of the HARQ-ACKcodebook includes a number of HARQ-ACK bits with each bit correspondingto one CBG, and a second portion of the HARQ-ACK codebook includes anumber of padded bits. The sum of the number of HARQ-ACK bits in thefirst portion and the number of padded bits in the second portion isequal to the determined HARQ-ACK codebook size. For example, the numberof HARQ-ACK bits in the first portion, e.g., M, is equal to the numberof CBGs actually received by a remote unit in initial transmission orretransmitted CBGs in retransmission between a base unit and the remoteunit. Assuming N is the RRC configured maximum number of CBGs of one TB,so (N−M) is the number of padded bits in the second portion of theHARQ-ACK codebook corresponding to the initial transmission orretransmission. All the above-mentioned implementations of fully usingthe (N−M) redundant bits in the HARQ-ACK codebook are applicable forthis embodiment.

FIG. 7 depicts an apparatus 700 according to the embodiments of thepresent application. The apparatus 700 includes one embodiment of theremote unit 101. Furthermore, the remote unit 101 may include a receiver701, a processor 702, and a transmitter 703. In some embodiments, thereceiver 701 and the transmitter 703 are combined into a single device,such as a transceiver. In certain embodiments, the remote unit 101 mayfurther include an input device, a display, a memory, and/or otherelements. In one embodiment, the receiver 701 receives a number of CBGsfrom a base unit 102, wherein each code block within a code block groupis independently decodable. The processor 702 determines a HARQ-ACKcodebook size corresponding to the number of code block groups. Thetransmitter 703 transmits a HARQ-ACK codebook to the base unit 102,wherein the HARQ-ACK codebook includes the first number of HARQ-ACK bitswith each bit corresponding to one code block group and a second numberof padded bits, wherein the first number plus the second number is equalto the determined HARQ-ACK codebook size. The functions andimplementations of all elements in the apparatus 700 and definitions ofrelated technical terms can refer to the specific descriptions of FIGS.2-5 and the foregoing corresponding paragraphs in this specification.

FIG. 8 depicts an apparatus 800 according to the embodiments of thepresent application. The apparatus 800 includes one embodiment of thebase unit 102. Furthermore, the base unit 102 may include a transmitter801, a processor 802, and a receiver 803. In some embodiments, thetransmitter 801 and the receiver 803 are combined into a single device,such as a transceiver. In certain embodiments, the base unit 102 mayfurther include an input device, a display, a memory, and/or otherelements. In one embodiment, a transmitter 801 transmits a number ofCBGs from to a remote unit, wherein each code block within a code blockgroup is independently decodable. The processor 802 determines aHARQ-ACK codebook size corresponding to the number of code block groups.The receiver 803 receivers a HARQ-ACK codebook from the remote unit 101,wherein the HARQ-ACK codebook includes the first number of HARQ-ACK bitswith each bit corresponding to one code block group and a second numberof padded bits, wherein the first number plus the second number is equalto the determined HARQ-ACK codebook size. The functions andimplementations of all elements in the apparatus 800 and definitions ofrelated technical terms can refer to the specific descriptions of FIGS.3-6 and the foregoing corresponding paragraphs in this specification.

The method of this disclosure can be implemented on a programmedprocessor. However, the controllers, flowcharts, and modules may also beimplemented on a general purpose or special purpose computer, aprogrammed microprocessor or microcontroller and peripheral integratedcircuit elements, an integrated circuit, a hardware electronic or logiccircuit such as a discrete element circuit, a programmable logic device,or the like. In general, any device on which there resides a finitestate machine capable of implementing the flowcharts shown in thefigures may be used to implement the processor functions of thisdisclosure.

While this disclosure has been described with specific embodimentsthereof, it is evident that many alternatives, modifications, andvariations will be apparent to those skilled in the art. For example,various components of the embodiments may be interchanged, added, orsubstituted in the other embodiments. Also, all of the elements of eachfigure are not necessary for operation of the disclosed embodiments. Forexample, one of ordinary skill in the art of the disclosed embodimentswould be capable of making and using the teachings of the presentapplication by simply employing the elements of the independent claims.Accordingly, the embodiments of the present application as set forthherein are intended to be illustrative, not limiting. Various changesmay be made without departing from the spirit and scope of the presentapplication.

In this document, relational terms such as “first,” “second,” and thelike may be used solely to distinguish one entity or action from anotherentity or action without necessarily requiring or implying any actualsuch relationship or order between such entities or actions. The terms“comprises,” “comprising,” or any other variation thereof, are intendedto cover a non-exclusive inclusion, such that a process, method,article, or apparatus that comprises a list of elements does not includeonly those elements but may include other elements not expressly listedor inherent to such process, method, article, or apparatus. An elementproceeded by “a,” “an,” or the like does not, without more constraints,preclude the existence of additional identical elements in the process,method, article, or apparatus that comprises the element. Also, the term“another” is defined as at least a second or more. The terms“including,” “having,” and the like, as used herein, are defined as“comprising.”

The following is what is claimed:
 1. A method comprising: receiving afirst number of code block groups from a base unit, wherein the firstnumber of code block groups are included in one transport block;determining a hybrid automatic repeat request acknowledgement codebooksize corresponding to the first number of code block groups;transmitting a hybrid automatic repeat request acknowledgement codebookto the base unit, wherein the hybrid automatic repeat requestacknowledgement codebook comprises a first number of hybrid automaticrepeat request acknowledgement bits with each bit corresponding to onecode block group and a second number of bits, wherein the first numberplus the second number is equal to the determined hybrid automaticrepeat request acknowledgement codebook size.
 2. The method of claim 1,further comprising receiving a signal from the base unit for indicatingthe hybrid automatic repeat request acknowledgement codebook size. 3.The method of claim 1, wherein the first number of hybrid automaticrepeat request acknowledgement bits is placed in the beginning of thehybrid automatic repeat request acknowledgement codebook and followed bythe second number of bits.
 4. The method of claim 1, wherein the secondnumber of bits are negative acknowledgement bits for padding.
 5. Themethod of claim 1, wherein the second number of bits is a portion of thefirst number of hybrid automatic repeat request acknowledgement bits. 6.The method of claim 1, wherein the second number of bits includes paritycheck bits of the first number of hybrid automatic repeat requestacknowledgement bits.
 7. The method of claim 1, wherein the secondnumber of bits includes a portion of cyclic redundancy check bits of thefirst number of hybrid automatic repeat request acknowledgement bits. 8.The method of claim 1, wherein the second number of bits includes arequest signaling for adjustment of a modulation and coding scheme. 9.An apparatus comprising: a receiver that receives a first number of codeblock groups from a base unit, wherein the first number of code blockgroups are included in one transport block; a processor that determinesa hybrid automatic repeat request acknowledgement codebook sizecorresponding to the first number of code block groups; a transmitterthat transmits a hybrid automatic repeat request acknowledgementcodebook to the base unit, wherein the hybrid automatic repeat requestacknowledgement codebook comprises a first number of hybrid automaticrepeat request acknowledgement bits with each bit corresponding to onecode block group and a second number of bits, wherein the first numberplus the second number is equal to the determined hybrid automaticrepeat request acknowledgement codebook size.
 10. The apparatus of claim9, wherein the second number of bits includes parity check bits of thefirst number of hybrid automatic repeat request acknowledgement bits.11. The apparatus of claim 9, wherein the second number of bits includesa request signaling for adjustment of a modulation and coding scheme.12. An apparatus comprising: a transmitter that transmits a first numberof code block groups to a remote unit; a processor that determines ahybrid automatic repeat request acknowledgement codebook sizecorresponding to the first number of code block groups; a receiver thatreceives a hybrid automatic repeat request acknowledgement codebook fromthe remote unit, wherein the hybrid automatic repeat requestacknowledgement codebook comprises a first number of hybrid automaticrepeat request acknowledgement bits with each bit corresponding to onecode block group and a second number of bits, wherein the first numberplus the second number is equal to the determined hybrid automaticrepeat request acknowledgement codebook size.
 13. The apparatus of claim12, wherein the transmitter transmits a signal to the remote unit forindicating the hybrid automatic repeat request acknowledgement codebooksize.
 14. The apparatus of claim 12, wherein the first number of hybridautomatic repeat request acknowledgement bits is placed in the beginningof the hybrid automatic repeat request acknowledgement codebook andfollowed by the second number of bits.
 15. The apparatus of claim 12,wherein the second number of bits are negative acknowledgement bits forpadding.
 16. The apparatus of claim 12, wherein the second number ofbits includes a portion of the first number of hybrid automatic repeatrequest acknowledgement bits.
 17. The apparatus of claim 12, wherein thesecond number of bits includes parity check bits of the first number ofhybrid automatic repeat request acknowledgement bits.
 18. The apparatusof claim 12, wherein the second number of bits includes a portion ofcyclic redundancy check bits of the first number of hybrid automaticrepeat request acknowledgement bits.
 19. The apparatus of claim 12,wherein the second number of bits includes a request signaling foradjustment of a modulation and coding scheme.
 20. The apparatus of claim12, wherein the second number of bits includes a channel qualityindicator.